package com.baomidou.kisso.common.bcprov.asn1;

import java.io.IOException;
import java.util.Enumeration;

/**
 * The DLSet encodes ASN.1 SET value without element ordering,
 * and always using definite length form.
 * <hr>
 * <h2>X.690</h2>
 * <h3>8: Basic encoding rules</h3>
 * <h4>8.11 Encoding of a set value </h4>
 * <b>8.11.1</b> The encoding of a set value shall be constructed
 * <p/>
 * <b>8.11.2</b> The contents octets shall consist of the complete
 * encoding of a data value from each of the types listed in the
 * ASN.1 definition of the set type, in an order chosen by the sender,
 * unless the type was referenced with the keyword
 * <b>OPTIONAL</b> or the keyword <b>DEFAULT</b>.
 * <p/>
 * <b>8.11.3</b> The encoding of a data value may, but need not,
 * be present for a type which was referenced with the keyword
 * <b>OPTIONAL</b> or the keyword <b>DEFAULT</b>.
 * <blockquote>
 * NOTE &mdash; The order of data values in a set value is not significant,
 * and places no constraints on the order during transfer
 * </blockquote>
 * <h3>9: Canonical encoding rules</h3>
 * <h4>9.3 Set components</h4>
 * The encodings of the component values of a set value shall
 * appear in an order determined by their tags as specified
 * in 8.6 of ITU-T Rec. X.680 | ISO/IEC 8824-1.
 * Additionally, for the purposes of determining the order in which
 * components are encoded when one or more component is an untagged
 * choice type, each untagged choice type is ordered as though it
 * has a tag equal to that of the smallest tag in that choice type
 * or any untagged choice types nested within.
 * <h3>10: Distinguished encoding rules</h3>
 * <h4>10.3 Set components</h4>
 * The encodings of the component values of a set value shall appear
 * in an order determined by their tags as specified
 * in 8.6 of ITU-T Rec. X.680 | ISO/IEC 8824-1.
 * <blockquote>
 * NOTE &mdash; Where a component of the set is an untagged choice type,
 * the location of that component in the ordering will depend on
 * the tag of the choice component being encoded.
 * </blockquote>
 * <h3>11: Restrictions on BER employed by both CER and DER</h3>
 * <h4>11.5 Set and sequence components with default value </h4>
 * The encoding of a set value or sequence value shall not include
 * an encoding for any component value which is equal to
 * its default value.
 */
public class DLSet extends ASN1Set {

	private int bodyLength = -1;


	/**
	 * create an empty set
	 */
	public DLSet() {
	}


	/**
	 * @param obj - a single object that makes up the set.
	 */
	public DLSet( ASN1Encodable obj ) {
		super(obj);
	}


	/**
	 * @param v - a vector of objects making up the set.
	 */
	public DLSet( ASN1EncodableVector v ) {
		super(v, false);
	}


	/**
	 * create a set from an array of objects.
	 */
	public DLSet( ASN1Encodable[] a ) {
		super(a, false);
	}


	private int getBodyLength() throws IOException {
		if ( bodyLength < 0 ) {
			int length = 0;

			for ( Enumeration e = this.getObjects() ; e.hasMoreElements() ; ) {
				Object obj = e.nextElement();

				length += ((ASN1Encodable) obj).toASN1Primitive().toDLObject().encodedLength();
			}

			bodyLength = length;
		}

		return bodyLength;
	}


	int encodedLength() throws IOException {
		int length = getBodyLength();

		return 1 + StreamUtil.calculateBodyLength(length) + length;
	}


	/**
	 * A note on the implementation:
	 * <p>
	 * As DL requires the constructed, definite-length model to
	 * be used for structured types, this varies slightly from the
	 * ASN.1 descriptions given. Rather than just outputting SET,
	 * we also have to specify CONSTRUCTED, and the objects length.
	 */
	void encode( ASN1OutputStream out ) throws IOException {
		ASN1OutputStream dOut = out.getDLSubStream();
		int length = getBodyLength();

		out.write(BERTags.SET | BERTags.CONSTRUCTED);
		out.writeLength(length);

		for ( Enumeration e = this.getObjects() ; e.hasMoreElements() ; ) {
			Object obj = e.nextElement();

			dOut.writeObject((ASN1Encodable) obj);
		}
	}
}